1. Field of the Invention
The present invention relates to the profile of a shadowless reflector for surgical lighting, and especially to a reflector's profile which can reflect the light rays produced from a single bulb all around an object and thereby eliminate shadows.
2. Description of the Prior Art
For the conventional operating lighting use to illuminate a patient during operations, it is hard to prevent the head shadow and hand shadow of surgeons from projecting onto the patient. The conventional surgical lighting is quite easy to influence a surgeon's sight. Therefore, the conventional operating lighting is required to be improved. The most common solution thereto is to arrange the light fixture with many mini-reflectors and bulbs, which are utilized to project cylindrical light rays. The projected cylindrical light rays have the same diameter and are focused on the same plane. However, the focusing datum plane and the light head distance must be adjusted when the distance of the light head and the operated position is changed. For this kind of light head, the individual adjustment of bulbs is very inconvenient in practice. In addition, compared with the conventional operating lighting, the structure of a light head of with mini-reflectors and bulbs is more complicated, the cost is higher, the weight is increased and the mobility is not good as well.
Consequently, a light fixture with one light source and a single large reflector is able to resolve the above problem of a plurality of mini-reflectors and bulbs. FIG. 1 shows the basic structure and the light path of the most common used conventional light head with single large reflector. The reflector 1 reflects the light rays scattered from the bulb 2 to a planed focusing datum plane and the light rays form a cylindrical illuminating range 4 so that each area in this illuminating range is illuminated by light rays projecting in only two-directions. Generally, partial light rays 5 are blocked at the place under the head position 9 of the surgeon position and near the lower position of the operating room light fixture. Due to the shadow caused by hands and instruments, it is therefore required to have a second or third light head to simultaneously project light rays on the same position to produce good shadowless effect.
It is also necessary that the light head with single large reflector should facilitate the movement of the position and the direction. Therefore, a handle 6 including a fixed disk-shaped portion 7 is mounted under the center of light head, which limits the illumination range of the light, sources. The lost diameter of the reflector .phi. Y, as shown in FIG. 1, must be larger than the diameter of the disk-shaped portion .phi. X because the lost angle of light source A is too large to make use of the light rays produced by the bulb, while the front-glass 8 of the operating light head also tends to reduce the brightness. In order to remove the filament figure and to enhance the well-distributed illumination in the illuminating range 4, the conventional light head with single large reflector makes use of a front glass 8 with wave lines to produce a softening effect. However, the penetrating rate of the visible light through the wave-shaped front glass 8 is approx. 50%, tremendously reducing the illumination in the illuminating range. Due to the effects described above, in addition to the disadvantage of bad shadowless effect, the waste of the light source results in the disadvantage that the brightness can't be further enhanced.